Jet engine variable area exhaust nozzle



May 5, 1953 c. R. BROWN ETAL JE'l1 ENGINE VARIABLE AREA EXHAUST NozzLE Filed April 26, 1951 |NVENTOR5 CHARLES R.BROWN WlLl- IAM H. LEEDECKE ATTORNEY I Patented May 5, 1953 UNITED STATES PTENT OFFICE 'JET 'ENGINE VARIABLE AREA EXHAUST NOZZLE Charles R. Brown, Glen Mills, and William-H.

lLeedeckc, Yeadon, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh,

`Pa.,a corporation oiPennsylvana Application April 26, 1951, .Serial N o. v223,110

V3' Claims.

This invention relates to. jet propulsion .power I plants, more particularly to such..power plants which .are equipped withvariable area exhaust nozzles, and has for an object to ,provide rimproved apparatusv of this character.

With some prior variable area exhaust nozzle constructions, particularly those of theV eyelid type, trouble has resulted from excessive leak:- age of hot exhaust gases between the iixed and the movable members of the nozzle, resulting in blow-by or hlow-back. Excessive `blowback maycause -air .frame overheating as well as drop in performance of the power plant land reduction in vlife et the parts of the exhaust nozzle.

The present invention prevents such excessive leakage of .hot gases and comprises a slotted construction of the fixed nozzle to provide terminal naps. The slots are overlapped by similar, but circumierentially-staggered, .napsformed by slotting a surrounding band or casing. Exhaust gas pressure within the nozzle holds the flaps against the eyelids, thereby preventing blow-by or blow-back. The slotted construction produces sufficient flexibility to permit the flaps to adjust to 'any irregularities or workings of the eyelid members.

Accordingly, vanother' 'obiect of the invention is to provide a iiexible seal between stationary and movable 'members of a variable area exhaust nozzle.

Another object of the invention is to provide an expandable and contractible seal between stationary and moving members of a variable area exhaust nozzle.

These and other objects are eiiected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a side elevational view of a gas turbine power plant incorporating the invention;

Fig. 2 is an enlarged fragmentary view, par tially in section, of the novel sealing structure; and

Fig. 3 is an enlarged fragmentary end view of the variable area exhaust nozzle shown in Fig. l.

The aircraft power plant il), shown for purposes of illustration only, comprises an annular outer casing I I and a composite inner core structure I2 coaxial therewith, the two being radially spaced to provide therebetween an annular passage I3 for flow of air and gases substantially straight through from an inlet I4 at the front, or left as viewed in Fig. 1, to an exhaust nozzle I5 at the rear or opposite end.

The composite core structure may include a iairing cone it at the inlet end, an axial .flow compressor Il', combustion apparatus i8, a gas turbine I9 .and a tailcone 2t. The turbine i9 may be connected to the compressor Il and drive the latter through shaft 22 jou-rnaled in `sui-table bearings 23.

A power plant of this type operates in accordance with well-known principles which may be summarized as follows.: Air entering the inlet It is compressed by the compressor il' and passes to the combustion apparatus l8- where its temperature .is raised by combustion of fuel therein. The heated air and hot l.products of combustion are expanded through the blading of the turbine it to motivate the latter land therethrough the compressor I l. The exhaust from the turbine discharges from the power plant through the exhaust nozzle I5 in the form of a jet for propelling the aircraft in, or on which, the power plant is mounted.

The present invention is concerned with the exhaust nozzle I5, which is shown in detail in Figs. 2 and 3.

An inner annular wall @il cooperates with the tailcone 2i) to define the downstream portion 0i' the annular gas ow passage i3. The downstream portion 3I of the annular wall 3d is surrounded, in juxtaposed relation, by an outer band or wall 32, the two walls kbeing welded to each other near the upstream end of the outer wall 32., as at 33.

Both walls 3i! and 32 are slotted longitudinally from their downstream terminal edges, as at 34 and 35, respectively, the slots 34 being staggered circumferentially relative to the slots 35, with the result that slots 3i of the inner wall 3l) are covered by flaps 3l of the outer wall 32 while the slots 35 of the outer wall 3?. are covered by the flaps 36 of the inner wall.

Inasmuch as the two sets of flaps 36 and 3l are unconnected to each other, except for the weld at 33 upstream thereof, the double-wall iiap construction is suiciently iiexible to expand and contract a limited amount to engage at all times the inner surfaces of a pair of nozzle eyelids lill pivotally mounted on the casing 30, as at di. These nozzle eyelids t may be conventional in structure and mode of operation, and hence a detailed description thereof is deemed unnecessary. lt should be suicient to state that they may be moved, at the will of the pilot or automatic control, between a first limit where the effective exhaust nozzle area is a maximum and a second position where the effective exhaust nozzle area is a minimum or any intermediate position.

At al1 positions of the eyelids 40 between these 3 limits the slotted double wall terminal portion engages the inner surfaces of the eyelids to effectively seal against leakage or blow-back of exhaust gases between the double wall 30-32 and the eyelids.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modications without departing from the spirit thereof.

What is claimed is:

1. A variable area exhaust nozzle for a jet propulsion power plant, comprising a first annular wall structure including a terminal portion slotted longitudinally from its downstream edge, considered in the direction of ow of exhaust gases through the nozzle, a second annular wall structure surrounding the slotted terminal portion of the rst annular wall structure in juxtaposed relation thereto, said second annular wall structure likewise being slotted longitudinally from its downstream edge, the slots ci each wall structure being staggered circumferentially with respect to the slots of the other wall strucn ture, whereby the slots or the i'lrst annular wall structure are covered by the material of the surrounding second wall structure, and a plurality of eyelid-type nozzle adjusting elements mounted for pivotal movement relative to the downstream edges of the iirst and second annular wall structures between a rst limit of maximum effective exhaust nozzle area and a second limit of minimum effective exhaust nozzle area, said nozzle-adjusting elements being sealingly engaged by the slotted terminal portions or" the f.-

juxtaposed annular wall structures in all positions of their pivotal movement.

2. A variable area exhaust nozzle for a let propulsion power plant, comprising an annular two-ply wall structure slotted longitudinally from its downstream end, considered in the direction of flow of exhaust gases through the nozzle, the slots of one ply being staggered circumferentially relative to the slots of the other ply, whereby the slots of each ply are covered by the material between the slots of the other ply, means uniting the two plys upstream of the slots only, and a plurality of nozzle area adjusting elements mounted externally of the annular wall structure for pivotal movement relative to the down- Cil - ing in juxtaposed relation the downstream portion of the inner annular casing, considered in the direction of flow of exhaust gases through said passage, means securing the upstream portion of the outer casing to the inner casing with the downstream portions of the two casings abutting but unsecured to each other, a plurality of nozzle area adjusting elements mounted exteriorly of said casings for movement between a first limit of maximum effective exhaust nozzle area and a second limit of minimum eiective exhaust nozzle area, the abutting unsecured downstream portions of the two casings being slotted axially from their downstream edges with the slots of each casing staggered circumferentially relative to those of the other casing, whereby they are rendered sufiiciently flexible to be expanded outwardly into sealing engagement with the nozzle area adjusting elements by pressure of exhaust gases in the ow passage.

CHARLES R. BROWN. WILLIAM H. LEEDECKE.

References Cited in the iile of this patent UNITED STATES PATENTS Number Name Date 851,603 Long Apr. 23, 1907 2,494,659 Huyton Jan. 17, 1950 2,551,372 Haltenberger May l, 1951 2,569,996 Kollsman Oct. 2, 1951 FOREIGN PATENTS Number Country Date 615,915 Great Britain Jan. 13, 1949 

